Methods of Dispersing Protein in Water

ABSTRACT

An easily dispersible granule of soybean protein comprises powdery soybean protein whose surface is coated with a carbohydrate, which is not readily digestible, wherein the carbohydrate is present in an amount of at least 5 parts by weight per 100 parts by weight of the powdery soybean protein. A method for preparing such an easily dispersible granule of soybean protein in which powdery soybean protein is granulated while the powder is sprayed with an aqueous solution containing a carbohydrate which is not readily digestible and which is characterized by using at least 5 parts by weight of the hardly digestible carbohydrate per 100 parts by weight of the powdery soybean protein is also disclosed. An Alternative method involves spraying a dry mix of soybean protein and not readily digestible carbohydrate with lecithin in water, and removing the water from the resultant lecithin-coated mix.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of prior, co-pending U.S. patentapplication Ser. No. 10/347,628 filed on Jan. 22, 2003, which itselfclaims priority as a continuation of U.S. patent application Ser. No.09/860,283 filed May 18, 2001, which itself claims priority as acontinuation-in-part to U.S. patent application Ser. No. 09/773,656,filed Jan. 31, 2001 (now U.S. Pat. No. 6,517,876), each of the contentsof the entirety which are incorporated by this reference.

FIELD OF THE INVENTION

The present invention relates to an easily dispersible granule ofsoybean protein and methods for the preparing thereof.

BACKGROUND OF THE INVENTION

Protein is a nutrient component essential for, among other things, theformation and maintenance of muscle. It has generally been said thatathletes should ingest protein in an amount ranging from 1.5 to 2.0 g/kgbody weight per day in order to reinforce the muscles and to enhancetheir stamina, although the amount varies depending on their age andliving environment (RINSHO EIYO (Clinical Nutrients), 1992, Vol. 80, No.5, pp. 495-502). More specifically, in case of a player whose bodyweight is 70 kg, it is necessary to take about 120 g of proteins perday. However, if such a large amount of protein is taken as the usualdiet, the total amount of the diet is considerably increased. As aresult, it would be painful for players to take a meal and he should bein excess training for preventing any accumulation of excess calorie asfats in the body. This may in turn become a cause of damage or shortenthe life of the player.

In addition, it is well known and understood that protein is anutritional requirement for all living things. While non-athletes maynot require as

For these reasons (and others), protein can be, and sometimes should be,supplemented from a source other than the usual meal, and accordingly,it has been planned to solve the foregoing problem by making use of aprotein-supply food having a high protein content. A variety of proteinscan be used as those for the protein-supply food, but it is one of themainstreams to use milk proteins and soybean proteins since they areparticularly high quality proteins. In particular, the soybean proteinshave become of major interest lately because of their low price.

Moreover, in recent studies (for instance, Federal Register, 64 FR57699, Oct. 26, 1999 (Food Labeling: Health Claim: Soy Protein andCoronary Heart Disease: Final Rule)), it is reported that a proteinintake of 25 g per day would show such effects as the reduction of thecholesterol content and the reduction of any risk of suffering fromheart diseases. Therefore, the efficacy of the soybean protein hasincreasingly attracted the interest of not only athletic sports players,but also healthy persons.

As foods capable of providing such soybean protein, there have beeninvestigated liquid foods such as soybean milk. However, the smellpeculiar to the soybean milk sometimes becomes a problem, and theseliquid foods also suffer from a problem of storability and portability.For this reason, it has recently become desirable to move from suchliquid foods to powdery soybean protein, which can easily be handled.

The powdery soybean protein may directly be ingested, but this is notcommon since it does not easily pass through the throat. It may likewisebe possible to first disperse the powdery soybean protein in a liquidsuch as water or milk and then drink the resulting dispersion in orderto make the intake thereof. However, the powdery soybean protein is in afine particulate condition and if it is added to a liquid, it suspendson the surface of the liquid to thus form the so-called “DAMA” (lumps ormasses). The phenomenon of this “DAMA” cannot easily be eliminated bysimply stirring with, for instance, a spoon. In other words, it isimpossible to make the powdery soybean protein drinkable simply byintroducing it into a liquid and then subjecting the mixture to simplestirring. Moreover, it is possible to convert the powdery soybeanprotein into a condition approximately similar to a drinkable liquid byintensively stirring such a mixture using a high speed-stirring machinesuch as a homogenizer, but this method is not generally performed. Evenif the powdery soybean protein is forced to disperse in a liquid usingsuch a method, the resulting dispersion is improved in the palatabilityand the ability to pass through the throat, but such problems as thesmell peculiar to the soybean, a bitter taste thereof, a harsh taste andastringency are not solved. Therefore, people are often reluctant todrink such dispersions.

Conventionally, powdery soybean protein has been prepared byspray-drying an aqueous solution of soybean protein per se, or afteradding lecithin to the aqueous solution. However, the soybean proteinproducts prepared according to these methods still suffer from theforegoing problems.

Other various methods for preparing powdery soybean protein productshave been reported, but none of them solve all of the foregoingproblems. For instance, Japanese Un-Examined Patent Publication No. Hei8-131083 discloses soybean protein powder prepared by blending or mixingan aqueous solution containing soybean protein for preparing solidifiedsoybean protein foods such as bean curd with a polyglycerin fatty acidester comprising a fatty acid having 8 to 18 carbon atoms and apolyglycerin having a degree of polymerization ranging from 4 to 10, andthen drying the resulting mixture. In the foregoing method for preparingsoybean protein powder, a synthetic surfactant is used instead oflecithin, which is a naturally occurring surfactant conventionally usedto improve the dispersibility of the soybean protein. This method wouldpermit the improvement of the dispersibility, but does not address tasteand/or palatability issues. In addition, Japanese Un-Examined PatentPublication No. Hei 8-131083 also discloses that the dried soybeanprotein powder may be granulated or formed into granules while using abinder such as sucrose, lactose, trehalose, dextrin or carboxymethylcellulose. Such granulation would permit the improvement of thedispersibility in, for instance, water. However, this procedure cannotsolve all of the problems concerning the smell, bitter taste, harshtaste and astringency peculiar to the soybean.

Furthermore, Japanese Un-Examined Patent Publication No. Hei 9-275911discloses a powdery soybean protein product prepared by adding 2 to 40parts by weight of starch hydrolyzate having a DE of 5 to 30 per 100parts by weight of the solid content of an aqueous solution containingsoybean protein components and then drying the resulting mixture. Inthis invention, the starch hydrolyzate having a DE of 5 to 30 isdispersed throughout the particles to thus improve the dispersibility ofthe soybean protein components in a liquid.

However, if the added amount of the starch hydrolyzate is insufficient,it takes a long period of time to completely disperse the soybeanprotein components in a liquid. On the other hand, if the added amountof the starch hydrolyzate is increased to ensure rapid dispersionthereof, the concentration of the soybean protein is reduced. Moreover,this method shows an effect of masking, for instance, the smell ofsoybean in the liquid to some extent, but it is insufficient in theeffect of improving astringency and rough feeling of the product.

In addition, Japanese Un-Examined Patent Publication No. Hei 8-154593proposes a method for preparing a soybean protein material comprisingthe steps of hydrolyzing an aqueous system containing soybean protein toa rate of hydrolyzing ranging from 5 to 20, adding 5 to 50 parts byweight of fats and oils to 100 parts by weight of the soybean proteinbefore or after the hydrolysis to form an emulsion, preferablydispersing an emulsifying agent, and drying the resulting emulsion. Inthis example, the decomposition of the protein and the addition of fatsand oils permits the improvement of the dispersibility and taste andtexture and the resulting product is suitable for use in makingconcentrated liquid such as soup and pickle liquids. However, if fatsand oils are added in such an amount that the smell, bitterness, harshtaste and astringency are replaced with the taste and texture of thefats and oils, the content of protein is reduced and therefore, theproduct is unfavorable as a protein-supply food.

Furthermore, there has been proposed a method for the preparation ofpowdery soybean protein, which makes use of granulation. For instance,Japanese Un-Examined Patent Publication No. Hei 6-113749 discloses amethod for fluidized bed-granulation, which comprises the step ofgranulating raw soybean protein powder while spraying the raw soybeanprotein powder with water or a water-containing liquid comprising, as asurfactant, a glycerin fatty acid ester, sorbitan fatty acid ester,propylene glycol and/or sucrose fatty acid ester. This method permitsthe improvement of the dispersibility of the resulting soybean proteinpowder, but does not solve the problems concerning the smell of soybeanand taste. In addition, if the added amount of such a surfactantincreases, the surfactant may adversely affect the taste of theresulting product.

Japanese Un-Examined Patent Publication No. Hei 9-215486 (BASIC EP78437A) discloses a method for preparing a granular food comprising thesteps of mixing a powdery raw material rich in carbohydrate and/orproteins with fats and oils or fats, further mixing the resultingmixture with a powdery raw material rich in carbohydrate and/or proteinsto give a powdery and/or dough-like mixture, which preferably comprises,as expressed in terms of part by weight, 5 to 95 parts of carbohydrate,up to 40 parts of proteins and up to 80 parts of oils or fats, and thenconverting the mixture into granules with supplemental use of steamand/or an aqueous solution of maltodextrin, gum or starch. The productprepared by this method has a high content of components other thanproteins and the method is not particularly developed for thegranulation of soybean proteins.

As has been discussed above, the soybean protein products preparedaccording to the foregoing methods are insufficient for use asprotein-supply foods and there is still room for improvement.

Japanese Un-Examined Patent Publication No. Hei 6-166622 discloses afood obtained by preferably incorporating hardly digestible dextrin intoa food having a high content of sugar or a sugar-containing preparationgranulated using hardly digestible dextrin. This patent also disclosesthat the sugar-containing preparation comprising the hardly digestibledextrin is effective for preventing obesity or abnormality of glucosetolerance and excellent in flowability and storability and therefore, itcan easily be used in not only food industries, but also generalfamilies.

SUMMARY OF THE INVENTION

It is accordingly an object of the present invention to provide easilydispersible soybean protein, which can uniformly be dispersed in aliquid within a short period of time and which gives a liquid dispersionfree of any rough feeling to the tongue, having good ability of passingthrough the throat, and also free of any unpleasant taste and texturesuch as the smell of soybean, harsh taste, bitter taste and astringency,upon drinking the same, as well as a method for preparing the easilydispersible soybean protein.

The inventors of this invention have conducted various studies to solvethe foregoing problems associated with the conventional techniques, havefound that the foregoing problems can efficiently be eliminated bycoating powdery soybean proteins with an aqueous solution ofcarbohydrate, and in particular saccharides, which are not readilydigestible, and then granulating the coated proteins.

Accordingly, the present invention relates to easily dispersible soybeanprotein granules, which comprise powdery soybean protein whose surfaceis coated with such a carbohydrate, wherein the carbohydrate is presentin an amount of at least 5 parts by weight per 100 parts by weight ofthe powdery soybean protein. The present invention also provides aneasily dispersible soybean protein granule wherein the coating of thenot readily digestible carbohydrate further comprises lecithin.

The present invention also provides a method for preparing an easilydispersible granule of soybean protein, which comprises the step ofgranulating powdery soybean protein while the powder is sprayed with anaqueous solution containing a carbohydrate which is not readilydigestible, characterized by using at least 5 parts by weight of thecarbohydrate per 100 parts by weight of the powdery soybean protein. Thepresent invention likewise provides the foregoing preparation methodwherein the aqueous solution containing the carbohydrate furthercomprises lecithin per 100 parts by weight of the powdery soybeanprotein. The present invention further provides the foregoingpreparation method wherein the granulation is fluidized bed-granulation.

In an alternative embodiment, the present invention also provides amethod for preparing the easily dispersible granule of soybean proteinin which a dry blend comprising soybean protein and a not readilydigestible carbohydrate is prepared, and is then sprayed with lecithinin water to produce a lecithin-coated soybean protein carbohydrateblend. The water is then removed from the lecithin-coated soybeanprotein/carbohydrate blend by drying. Other components, includingnutraceutical components such as sterols, steryl esters, stanols, stanolesters, isoflavones, vitamins, minerals, and the like, can be combinedwith the protein/carbohydrate/lecithin blend to further supplement thenutritive value of the product.

The easily dispersible soybean protein granule of the present inventionpossesses the following characteristic properties:

1. It can be dispersed in usual liquids for drinking such as water,milk, sour milk beverages and fruit juice drinks, without formingso-called “DAMA.”

2. It can be dispersed in the foregoing liquids within a short period oftime.

3. Even if one keeps the dispersion in his mouth immediately after thepreparation thereof, it does not have rough feeling to the tongue andeasily passes through the throat.

4. It can eliminate any unpleasant taste such as the smell of soybean,harsh taste, bitter taste and astringency upon drinking the resultingdispersion.

As has been described above, the easily dispersible soybean proteinaccording to the present invention is easily dispersed in a liquid andthe resulting liquid dispersion is quite easily drinkable. Therefore,the soybean protein can favorably be used in particular asprotein-supply foods.

DETAILED DESCRIPTION OF THE INVENTION

The easily dispersible soybean protein granules and the method for thepreparation thereof according to the present invention will hereunder bedescribed in more detail.

The easily dispersible soybean protein granule of the present inventionis one comprising powdery soybean protein, the surface of which iscoated with a carbohydrate which is not readily digestible, andcomprises the carbohydrate in an amount of at least 5 parts by weightand more preferably at least 9 parts by weight per 100 parts by weightof the powdery soybean protein.

The easily dispersible soybean protein granule of the present inventioncan be prepared by using at least 5 parts by weight and more preferablyat least 9 parts by weight of carbohydrate or saccharides per 100 partsby weight of powdery soybean protein, and granulating the powderysoybean protein while spraying the soybean protein with an aqueoussolution containing the carbohydrate. As a result, the easilydispersible soybean protein granule has a structure comprising soybeanprotein powder whose surface is coated with the carbohydrate. In thisconnection, it is important to use the carbohydrate in the form of anaqueous solution and to bring the powder into close contact with theaqueous solution. More specifically, the easily dispersible soybeanprotein granule of the present invention can be prepared by stirring andfluidizing powdery soybean protein according to an appropriate method,spraying the stirred and fluidized powdery soybean protein with thecarbohydrate in the form of an aqueous solution, followed byappropriately drying the spray-coated soybean protein powder after thespraying step or simultaneous with the spraying operation to thus coatthe surface of the soybean protein powder with the carbohydrate and tosimultaneously granulate the soybean protein.

Such granulation of the soybean protein may be performed using a methodsuch as those used for granulation in the fields of foods and medicine,stirring granulation, extrusion granulation and fluidized-bedgranulation. Among these, the fluidized-bed granulation technique ismore preferred as compared with other methods. This is because theformer permits the simultaneous execution of the spraying of the aqueoussolution, granulation and drying and thus, the rate of penetration ofthe carbohydrate into the interior of the soybean protein is low. Thisresults in a structure in which the surface of the soybean protein iscoated with the carbohydrate.

Specific examples of the fluidizing devices usable in the granulation ofthe present invention are fluidized-bed granulation devices such asbatch-wide fluidized-bed devices, jet fluidized-bed devices and jetfluidized-bed granulation devices (Granulation Handbook, 1991, pp.295-303).

The temperature of warmed air (suction air) used in the fluidized-bedgranulation is adjusted to the range of from 30 to 100° C. andpreferably 50 to 80° C., while the temperature of the raw materialsduring the granulation is controlled to the range of from 25 to 70° C.and preferably about 30 to 50° C. This is because if the temperature istoo high, it is difficult to carry out granulation, while if it is toolow, it is difficult to fluidize the raw materials.

The spraying speed during the granulation step may vary depending on thekinds of the fluidized-bed devices selected and the flow rate of thesolution is usually controlled to a level of about 0.5 to 4 1/min, butit is not restricted to any specific level.

The drying step may be carried out simultaneous with the fluidization ormay be a step subsequent to the fluidization step. When the drying isperformed simultaneously with the fluidization, the drying temperaturepreferably ranges from 30 to 50° C. On the other hand, if the drying iscarried out after the spraying step, the drying is preferably carriedout at a temperature ranging from 50 to 70° C.

After completion of the drying, the resulting granules are passedthrough a sieve, for instance, to make the particle size uniform andthen packaged. The granules come in contact with the air during theclassification step to thus air-cool the same and therefore, thegranules are not necessarily forced to cool. However, cooled air is, ifnecessary, passed through the granules to thus reduce the temperature ofthe granules to about 30 to 50° C., depending on the packaging materialsused.

As has been described above, the easily dispersible soybean proteingranule of the present invention comprises soybean protein having suchproperties that it is easily drinkable after dispersing it in a liquid.In this respect, such properties relate to, in particular, the amount ofthe carbohydrate relative to that of the powdery soybean protein. Thesoybean protein granule of the present invention must comprise at least5 parts by weight and more preferably at least 9 parts by weight of thecarbohydrate per 100 parts by weight of the powdery soybean protein. Theeffect of the addition of the carbohydrate is not changed even if it isused in a considerably large amount and, therefore, the upper limitthereof is not necessarily critical. For example, it may in general beused in an amount of up to 100 parts by weight. However, the soybeanprotein granule is used as a protein-supply food, the amount of thecarbohydrate is preferably not more than 30 parts by weight and morepreferably not more than 15 parts by weight so that the content of thesoybean protein in the granule is not substantially reduced.

In addition, the carbohydrate not readily digestible, is used forcoating the powdery soybean protein in the form of an aqueous solutionhaving a concentration preferably ranging from 5 to 50% by mass and morepreferably 8 to 30% by mass. If the concentration of the aqueoussolution is less than 5% by mass, a large amount of the liquid to besprayed is required and this in turn reduces the production efficiency.On the other hand, if the concentration exceeds 50% by mass, there wouldbe such a tendency that the granulation of the soybean protein powder isimpaired.

In this respect, it is sufficient to use the carbohydrate in thegranulation step in an amount of at least 5 parts by weight and morepreferably at least 9 parts by weight per 100 parts by weight of thepowdery soybean protein. Moreover, one skilled in the art wouldrecognize that it would be appropriate to adjust the content of thecarbohydrate in the resulting granule by changing the other granulationconditions and thus, the upper limit of the amount of the carbohydrateused in the granulation step is not necessarily fixed.

The amount of carbohydrate used in the present invention is higher thanthat required for using the same as a simple binder and accordingly, theamount of the aqueous solution to be added is also increased. However,such an amount of the carbohydrate is required for forming a film on thesurface of the powdery soybean protein to thus ensure the effect of thepresent invention. In this connection, whether the surface of thepowdery soybean protein is properly coated with the carbohydrate can beexamined or detected by staining the granules with an iodine solution.

The soybean protein used in the present invention may be a powderysoybean protein product prepared from defatted soybean by a variety ofart-recognized methods, which can increase the protein content. Specificexamples thereof include extracted protein having a soybean proteincontent ranging from 50 to 60% by mass, concentrated soybean proteinhaving a soybean protein content ranging from 60 to 70% by mass, andisolated soybean protein having a soybean protein content of not lessthan 90% by mass. Among them, preferred are isolated soybean proteinproducts because of their high soybean protein contents. Alternatively,it is also possible to use the foregoing soybean protein productsslightly hydrolyzed to such an extent that they do not have extremebitterness and rough taste. In cases where such hydrolyzed soybeanprotein is used, the viscosity of a solution of the product obtainedafter the granulation can be controlled. As a result, this is quitepreferred since the resulting easily dispersible soybean protein can bedispersed in a liquid in a high concentration.

Regarding the particle size of the soybean protein, preferably usedherein are those comprising fine particles in a high rate and it isdesirable in the present invention to use those in which the rate ofparticles capable of passing through a sieve of 100 mesh exceeds 90% bymass.

The term “not readily digestible carbohydrate or saccharides” usedherein means those having a content of “not readily digestiblecomponents” of not less than 30% by mass, as determined by the methoddefined below. The phrases “not readily digestible” and “hardlydigestible” are used interchangeably herein.

Method for Quantitative Analysis of Not Readily Digestible Components: Anot readily digestible carbohydrate sample (1 g) was accurately weighedout, followed by addition of 50 ml of a 0.05M phosphate buffer (pH 6.0),then 0.1 ml of alpha-amylase (Termamil 120 L, titer: 120 KNU/g,available from Novo Nordisk Bio-industry Company), and carrying out areaction at 95° C. for 30 minutes. After cooling the reaction system,the pH value thereof is adjusted to 4.5, followed by addition of 0.1 mlof amyloglucosidase (No. A-3042, titer: 6100 U/ml, available from SigmaCompany), reacting them at 60° C. for 30 minutes and then raising thetemperature of the reaction system up to 90° C. thus terminate thereaction. After the completion of the reaction, the reaction solution isfilled up to 100 ml with water, determination of the amount of glucose(B) (g) by the pyranose-oxidase method (Starch Science, Vol. 37, No. 2,p. 107), determination of the amount of glucose (A) (g) prior to thereaction to thus calculate the content of the hardly digestiblecomponents (%) according to the following equation:

Content Not Readily Digestible Components (%)=[1−A−(B−A)×0.9]×100 (Inthis equation, A represents the amount (g) of glucose prior to thereaction and B represents the amount (g) of glucose after completion ofthe reaction).

For example, the not readily carbohydrate used in the present inventioncan be prepared by treating roasted dextrin with alpha-amylase, ortreating the roasted dextrin with, for instance, a variety of enzymessubsequent to the treatment with alpha-amylase, and then subjecting, ifnecessary, the treated dextrin to a treatment such as fractionation, anion-exchange resin chromatography treatment and/or a purificationtreatment. In other words, the process for preparing the not readilydigestible carbohydrate comprises a step for preparing roasted dextrinas an intermediate and a step for producing the carbohydrate productstarting from the resulting roasted dextrin. In this respect, the starchserving as a raw material for the roasted dextrin and used as a startingmaterial for the carbohydrate is not restricted to any specific one andmay be, for instance, potato starch, corn starch, waxy corn starch,tapioca starch, wheat starch and rice starch. The method for preparingthe not readily digestible carbohydrate will hereunder be described inmore detail.

The roasted dextrin can be prepared by adding, to starch, a mineral acid(such as hydrochloric acid, nitric acid, sulfuric acid) and preferablyhydrochloric acid, for instance, a 1% by mass aqueous hydrochloric acidsolution, in an amount ranging from 3 to 10% by mass per 100 parts byweight of the starch and then heat-treating the resulting mixture. Priorto the heat-treatment, it is preferred that the mixture of the starchand the aqueous mineral acid solution be stirred in an appropriate mixerin order to uniformly admix the mixture and then ripened (over severalhours), followed by pre-drying of the mixture preferably at atemperature ranging from about 100 to 120° C. to thus reduce themoisture present in the mixture down to about 5% by mass. Theheat-treatment is suitably carried out at 150 to 200° C. to 10 to 120minutes, preferably 30 to 120 minutes. The higher the temperature of theheat-treatment, the higher the content of the not readily digestiblecomponent present in the target product. However, if using a temperatureof not less than 180° C., there is a tendency of forming a coloredsubstance and therefore, the temperature for the heat-treatment is morepreferably 150 to 180° C.

It is also possible to carry out the reaction at a high temperature fora shorter period of time by appropriately selecting a heating device tobe used. For instance, a device in which a uniform reaction can becarried out within a short period of time such as an extruder may beused to ensure the efficient heat-treatment. Such a method, which makesuse of an extruder, is disclosed in Japanese Un-Examined PatentPublication No. Hei 06-80701.

The not readily digestible carbohydrate is prepared from the roasteddextrin prepared according to the foregoing method. More specifically,the roasted dextrin is dissolved in water to give an aqueous solutionhaving a concentration ranging from about 20 to 45% by mass, followed byadjustment of the pH of the roasted dextrin aqueous solution to therange of from 5.5 to 6.5, and treatment of alpha-amylase such asTarmamil 60L (trade name, available from Novo Nordisk Bio-industryCompany) with roasted dextrin alpha-amylase. This alpha-amylase is addedto the roasted dextrin in an amount ranging from 0.05 to 0.2% by massbased on the amount of the dextrin. In case where other alpha-amylasesare used, an equivalent amount of each enzyme is added thereto, whiletaking into consideration the titer of each enzyme. After the additionof alpha-amylase, the solution is heated to carry out the hydrolysis atthe working temperature of the alpha-amylase ranging from 85 to 100° C.(the working temperature may vary depending on the kinds ofalpha-amylases) for a time ranging from 30 minutes to 2 hours. Then thetemperature is raised up to about 120° C. (the deactivation temperatureof the alpha-amylase) to thus interrupt the effect of the alpha-amylase.At this stage, it is also possible to reduce the pH value to a level atwhich the alpha-amylase undergoes deactivation, i.e., to a pH of about 4by the addition of an acid such as hydrochloric acid or oxalic acid.

In case where the reaction product is purified after the completion ofthe treatment with the alpha-amylase, activated carbon is added theretoin order to remove any impurity and undesirable color. Subsequently, thereaction product is filtered through the usual filter-press or apre-coat filter. Then the reaction product is treated with anion-exchange resin to remove salts and colored substances present in thesolution. The treatment with an ion-exchange resin is desirably carriedout by the use of a cation-exchange resin, an anion-exchange resin andsubsequently by passing through a mixed resin comprising cation- andanion-exchange resins. This method permits the preparation of acarbohydrate which is not readily digestible containing about 30 to 85%by mass of hardly digestible components depending on the kind of roasteddextrin.

After the treatment with alpha-amylase, the roasted dextrin may furtherbe treated with other enzymes. When the enzyme treatment is a treatmentwith glucoamylase, this enzyme treatment may be carried out undercondition of the usual glucoamylase treatment. For instance, thetemperature of the reaction solution is reduced to 55 to 60° C., the pHvalue thereof is adjusted to about 4.0 to 6.0, commercially availableglucoamylase is added to the roasted dextrin in an amount of about 0.05%by mass based on the weight of the dextrin and the dextrin is hydrolyzedfor about 24 to 48 hours, while maintaining the foregoing temperature ofthe reaction solution. In this reaction, the digestible components suchas oligosaccharides present in the solution are decomposed into glucose.The added amount and working time of glucoamylase are not restricted tothe foregoing ranges and it is sufficient to add the same in anequivalent amount depending on the titer of the amylase. In addition,the reaction time may arbitrarily be controlled by increasing orreducing the amount of the enzyme to be added. Subsequently, thereaction system is heated to a temperature of about 80° C. to thusterminate the hydrolysis. Then the resulting product is if necessarypurified according to the method identical to that described above. Theproduct obtained by this preparation method contains glucose in additionto the not readily digestible components.

In this connection, a small amount of alpha-amylase coexists in theusual glucoamylase and therefore, an effect can be expected, which isapproximately similar to that achieved by the simultaneous use ofalpha-amylase and glucoamylase. However, the effect of alpha-amylase mayoften be lowered depending on the amount of the coexisting alpha-amylaseand therefore, it is preferred to treat the roasted dextrin withalpha-amylase and subsequently with glucoamylase.

In most of cases, the glucoamylase treatment does not directly increasethe content of the hardly digestible components, but the treatmentconverts digestible components such as oligosaccharides into glucose andthe resulting glucose component is separated and removed by, forinstance, ion-exchange resin chromatography to thus increase the contentof the not readily digestible components. The ion-exchange resinchromatography is a technique for removing glucose by passing through anion-exchange resin for separation, a solution obtained by treating theroasted dextrin with glucoamylase, decoloring and filtering theresulting solution and then purifying it with an ion-exchange resin.Examples of ion-exchange resins usable herein are commercially availableusual strongly acidic cation exchange resins such as Amberlite IR-110,Amberlite IR-118, Amberlite IR-120 (trade names of the productsavailable from Organo Company), Diaion 2K-110, Diaion SKK-102 (tradenames of the products available from Asahi Chemical Industry Co., Ltd.).The flow rate upon passing the solution through the column is preferablycontrolled depending on the specific resin used, but the solution is fedto the column at an SV ranging from 0.1 to 0.6, preferably 0.2 to 0.4and a temperature ranging from 20 to 70° C., preferably 50 to 70° C.This separation treatment can increase the content of the hardlydigestible components to not less than about 80% by mass and preferably85 to 95% by mass or higher and can reduce the glucose content to about0.5% by mass.

The not readily digestible carbohydrate may include the not readilydigestible dextrin prepared by the foregoing method and not readilydigestible starch syrup as well as reduced products thereof. Examples ofthe not readily digestible carbohydrates commercially available are PineFiber (trade name of not readily digestible dextrin available fromMatsutani Industry Co., Ltd., content of hardly digestible components:50 to 60% by mass), Fibersol 2 (trade name of hardly digestible dextrinavailable from Matsutani Industry Co., Ltd., content of hardlydigestible components: 85 to 95% by mass), and Fibersol 2H (trade nameof reduced, hardly digestible dextrin available from Matsutani IndustryCo., Ltd., content of hardly digestible components: not less than 85% bymass). Alternate forms of the not readily digestible carbohydrateinclude, but are not necessarily limited to, beta-glucan, inulin,hemicellulose, and the like.

The soybean protein granules prepared by the foregoing granulationmethod would effectively allow the achievement of the intended effect.However, it is preferred that the granulation be carried out using anaqueous solution of the carbohydrate to which lecithin is added. This isbecause the resulting dispersion may smoothly pass through the throatupon drinking. In this respect, the added amount of lecithin preferablyranges from 0.4 to 2.0 parts by weight per 100 parts by weight of thepowdery soybean protein.

If lecithin is added to the aqueous solution in an amount of less than0.4 part by weight per 100 parts by weight of the powdery soybeanprotein, the foregoing effect is almost identical to that observed whenlecithin is not used. On the other hand, if the amount of lecithinexceeds 2.0 parts by weight, the time required for dispersing lecithinin the aqueous solution of the carbohydrate is increased and/or thecontent of the soybean protein is reduced. For this reason, the upperlimit of lecithin is desirably set at this level.

Lecithin used in the present invention may be any one commonly used asadditives for foods such as soybean lecithin or yolk lecithin, but hesoybean lecithin is more preferably used since it is less expensive andhas good compatibility to the soybean protein. Among the soybeanlecithin products, crude lecithin has a high content of fats and oils orthe like and has smells and tastes peculiar thereto and is not easilyformed into a paste-like or plastic-like state. On the other hand,purified lecithin and enzyme-treated lecithin are more preferably usedin the present invention, since they are in powdery states, can easilybe handled and are excellent in dispersibility and solubility in water.

The easily dispersible soybean protein granule of the present inventionis a protein-supply food prepared using a not readily digestiblecarbohydrate and lecithin in a ratio specified above. It is alsopossible to arbitrarily increase the amount of the carbohydrate used upto a level almost equal to that of the powdery soybean protein. Thiswould permit the enhancement of a variety of physiological functionswhich may be attributable to the carbohydrate, such as the reduction ofcholesterol, the inhibition of insulin secretion, the inhibition of anyincrease in the blood-sugar level, the intestinal function-controllingaction, the prevention of carcinoma of large intestine, heart diseasesand cerebral apoplexy and the inhibition of the excretion of harmfulsubstances. In this regard, it is desirable to spray the powdery soybeanprotein with the hardly digestible carbohydrate in the form of anaqueous solution containing about 15 parts by weight per 100 parts byweight of the powdery soybean protein and to preliminarily mix theremaining carbohydrate with the powdery soybean protein. As has beendescribed above, if the rate of the hardly digestible carbohydrate to beadded in the form of an aqueous solution is increased, the time requiredfor passing the solution through a column and that required for dryingthe resulting granular product are increased.

Moreover, it is also possible to incorporate, into the easilydispersible soybean protein granule of the present invention, tracecomponents such as vitamins and minerals, which are components effectivefor the human body. In this respect, vitamins and minerals insoluble inwater are preliminarily mixed with the powdery soybean protein and thenthe resulting mixture is sprayed with an aqueous solution containing thenot readily digestible carbohydrate. On the other hand, vitamins andminerals soluble in water may be dissolved in an aqueous solution of thecarbohydrate and then sprayed on the powdery soybean protein.Alternatively, an aqueous solution of these trace components isseparately sprayed on the powdery soybean protein prior to or after thespray of the aqueous solution of the carbohydrate to thus carry out thegranulation.

The term “easily dispersible soybean protein granule” used herein meansa soybean protein granule capable of being uniformly dispersed in theusual liquid for drinking such as water, milk, sour milk beverages andfruit juice drinks within a short period of time, for instance, withinabout 10 seconds and more preferably within about 5 seconds.

Examples of liquid in which the easily dispersible soybean proteingranule of the present invention is dispersed are water, milk, sour milkbeverages and fruit juice drinks, but the present invention is notrestricted to these specific examples. The amount of the easilydispersible soybean protein granule of the present invention to be addedto the liquid is not restricted to any specific range, but the besteffect of the resent invention can be expected when the amount thereofin general ranges from about 50 to 150 g/l.

Now, an example of the method for preparing the easily dispersiblesoybean protein granule, which makes use of a fluidized bed, will begiven below in order to more specifically describe the presentinvention.

The powdery soybean protein is introduced into a fluidized bedgranulation device and an aqueous solution containing 5 to 50% by mass,preferably 8 to 30% by mass of not readily carbohydrate is sprayed onthe powdery soybean protein till the amount of the carbohydrate is atleast 5 parts by weight per 100 parts by weight of the powdery soybeanprotein, while the powdery soybean protein is fluidized by injectingwarmed air maintained at a temperature of about 50 to 80° C. It is morepreferred that lecithin be dispersed in the aqueous solution in anamount ranging from 0.4 to 2 parts by weight per 100 parts by weight ofthe powdery soybean protein. In addition, minerals such as iron andcalcium salts in the form of powder may if necessary be admixed with thepowdery soybean protein in advance or they may be dissolved or dispersedin the aqueous solution containing the hardly digestible carbohydrate.

After spraying all of the aqueous solution, the soybean protein thussprayed is dried till the temperature of the product reaches about 50 to60° C., then cooled by supplying cold air maintained at 20 to 30° C.till the temperature of the product is reduced to 35 to 45° C. to thuscomplete the granulation and drying steps. The spraying temperature andthe spraying speed are controlled in such a manner that the particlesize of the product ranges from about 90 to 500 μm and preferably 120 to350 μm.

The resulting easily dispersible soybean protein granule can rapidly bedispersed in a liquid such as water and milk. The resulting dispersiondoes not provide any rough feeling to the tongue or mouth, easily passesthrough the throat upon drinking it without any pre-treatment and onecan drink the same without any trouble and unpleasant feeling, as thoughthey were drinking the liquid per se.

In an alternative embodiment of the present invention, the easilydispersible soybean protein granule of the invention can be produced byforming a dry blend of the soy protein with a selected not readilydigestible carbohydrate. The ratio of not readily digestiblecarbohydrate to soy protein can range from about 0.1:10 to about 10:10.A preferred range is from about 0.5:10 to about 1.5:10. In thisembodiment, the dry blend is then sprayed with a mix of lecithin andwater, in a range of from about 1% lecithin in water to about 10%, andin a preferred range of from about 3% lecithin in water to about 5%,using agglomeration techniques that are conventional in the art. Thelecithin/water blend is then added to the dry blend so that the ratio oflecithin to dry blend is from about 0.1:100 to about 2.0:100. A morepreferred ratio of lecithin to dry blend is form about 0.5:100 to about1.5:100. The water is then removed by heating the resulting blend sothat the water is removed but the volubility of the soy protein is notdecreased. Those of ordinary skill in the art will recognize that thetemperature or temperatures at which this drying process is carried out,and the duration of the drying process, will vary depending upon theamount of water used, the amount of material being dried, and the like.The resultant dried product is readily dispersed in water with stirring,and the product produces a beverage that is smooth and free of lumps.The high solubility of the protein is confirmed as there is only aslight reduction in Nitrogen Solubility Index in the product.

The present invention will hereunder be described in more detail withreference to the following Examples. In these Examples, “part” means“part by weight” unless otherwise specified.

EXAMPLE 1

To a small-sized fluidized bed device (a granulation device forlaboratories Model 20L available from Ogawara Manufacturing Company),there was added 100 parts of ProFam 891 (trade name of isolated soybeanprotein available from ADM Company, particle size: not less than 90% bymass of 100 mesh pass). Then the powdery soybean protein was sprayedwith a solution prepared by adding hardly digestible carbohydrate andlecithin in a ratio specified in the following Table 1 to 100 parts ofwater, while fluidizing the soybean protein using warmed air of 65° C.to thus granulate the soybean protein.

The carbohydrate used in this Example was Fibersol 2 (trade name ofhardly digestible dextrin available from Matsutani Chemical IndustryCo., Ltd., content of hardly digestible components: about 90% by mass).Lecithin used herein was Ultralec P (trade name of purified soybeanlecithin available from ADM Company, content of acetone insolubles: notless than 97%). The solution for spraying was prepared by dissolving thecarbohydrate in water and then dispersing lecithin in the resultingaqueous solution. Separately, the same procedures used above wererepeated except that Pinedex #2 (trade name of maltodextrin availablefrom Matsutani Chemical Industry Co., Ltd., content hardly digestiblecomponents: about 3%) was substituted for the hardly digestiblecarbohydrate, as Comparative Example, to granulate the soybean protein.

After all of the solution was sprayed on the soybean protein, thesprayed soybean protein was dried until the temperature thereof reached55° C., then cooled by supplying cold air of 25° C. until thetemperature of the soybean protein reduced to 40° C. to thus completethe granulation and drying steps. As a result, granulated products shownin Table 1 (Sample 1 to Sample 8) were obtained.

Moreover, 100 parts of ProFam 891 and 10 parts of Fibersol 2 were mixedtogether in their powdery state, the resulting powdery mixture wasintroduced into a fluidized bed to thus fluidize it, a lecithindispersion prepared by dispersing one part of Ultralec P in 100 parts ofwater was sprayed on the fluidized mixture in the same manner used aboveto granulate the mixture and to thus give a granulated product or Sample9.

The dispersibility of the granulated products and the conditions of theresulting dispersions upon drinking were evaluated according to thefollowing evaluation criteria. The results thus obtained are summarizedin the following Table 2.

Dispersibility: To a 300 ml volume beaker, there were added 200 ml ofwater of 20° C. and then 10 g of each sample at a time, then theresulting mixture was stirred with a spoon to observe the dispersedstate of the sample.

The sample was dispersed by stirring for 5 seconds.

: The sample was dispersed by stirring for 10 seconds.

: When stirring for 10 seconds, DAMA was partially formed.

X: When stirring for 10 seconds, a considerable amount of DAMA wasformed.

Palatability: To a 300 ml volume beaker, there were added 200 ml ofwater of 20° C. and then 10 g of each sample at a time, then theresulting mixture was stirred with a spoon for 10 seconds and thefeeling to the tongue or mouth upon including the resulting dispersionin the mouth was evaluated.

*: Quite smooth

: Smooth

: There was observed rough feeling to the mouth

X: There was observed considerable rough feeling to the mouth.

Ability of Passing Through the Throat: Each sample was dispersed in thesame manner used for the evaluation of “Palatability,” followed bydrinking the resulting dispersion as such to thus evaluate the abilityof the same to pass through the throat.

*: The dispersion easily passed through the throat and thus it was neveraccompanied by any trouble upon drinking.

: The dispersion exhibited powdery feeling to some extent, but wasdrinkable without any problem.

: The dispersion exhibited powdery feeling and one would be reluctant toswallow the dispersion.

X: The dispersion showed considerable powdery feeling and it wasdifficult to easily swallow the same.

Taste and Texture: Each sample was dispersed in the same manner used forthe evaluation of “Palatability,” followed by comparison of the tasteand texture observed upon drinking with that of milk.

*: The taste and texture were almost identical to those observed formilk and one was never reluctant to swallow the same.

: The taste and texture were approximately identical to those observedfor milk and one was never reluctant to swallow the same.

: The dispersion slightly had unpleasant tastes such as bitterness,harsh taste and astringency, which were not observed for milk and onewould be reluctant to swallow the dispersion.

X: The dispersion considerably had unpleasant tastes such as bitterness,harsh taste and astringency, which were not observed for milk and onewould be quite reluctant to swallow the dispersion. TABLE 1 Sample Kindof Amount of Amount of No. Carbohydrate Carbohydrate Lecithin Sample 1 —— — Sample 2 Fibersol 2  6 parts — Sample 3 Fibersol 2 10 parts — Sample4 Fibersol 2 10 parts 0.5 part Sample 5 Fibersol 2 10 parts 1.7 partSample 6 Fibersol 2 13 parts — Sample 7 Pinedex #2 10 parts — Sample 8Fibersol 2  2 parts —

TABLE 2 Dispers- Paya- Ability of passing Taste and Granule ibilitybility through Throat Texture Con- Sample X X X X trol 1 Exam- Sample

ple 2 Exam- Sample

*

* ple 3 Exam- Sample * * * * ple 4 Exam- Sample * * * * ple 5 Exam-Sample

*

* ple 6 Comp. Sample

‡ ‡ X Ex. 7 Comp. Sample ‡ ‡ ‡ ‡ Ex. 8 Comp. Sample ‡ ‡ ‡

Ex. 9

EXAMPLE 2

The procedures used in Example 1 were repeated except that juice wassubstituted for the milk used in Example 1 to evaluate the soybeanprotein granule. As a result, there were observed results approximatelyidentical to those obtained in Example 1.

EXAMPLE 3

ProFam 891 (100 parts) was fluidized and the fluidized ProFam 891 wassprayed with a solution prepared by adding, to 100 parts of water, 12parts of Fibersol 2H (trade name of reduced hardly digestible dextrinavailable from Matsutani Chemical Industry Co., Ltd., content of hardlydigestible components: 88% by mass) and 0.8 part of Ultralec P(lecithin) to thus granulate the ProFam 891 according to the method usedin Example 1.

The resulting soybean protein granule was evaluated according to Example1 and as a result, it was found that the granule showed approximatelythe same results observed for the granule prepared using Fibersol 2 andlecithin in Example 1.

EXAMPLE 4

ProFam 891 (100 parts) and calcium lactate pentahydrate (3 parts) weremixed together in their powdery state, the resulting mixture wasintroduced into a fluidized bed to thus fluidize the same. Then thefluidized mixture was sprayed with a solution prepared by adding, to 100parts of water, 8 parts of Fibersol 2 and 1.2 part of Ultralec P in anamount of ⅔ time the total volume of the solution prepared and thespraying was once interrupted. To the remaining solution, there wereadded 0.005 part of vitamin B1, 0.006 part of vitamin B2 and 0.012 partof vitamin B12 and then the spraying operation was again initiated. Thegranulation was performed according to the method used in Example 1,except that the spraying operation was once interrupted.

EXAMPLE 5

Five thousand pounds of soy protein isolate was dry blended with 500pounds of a not readily digestible carbohydrate; in this instance,Fibersol. A de-oiled lecithin was added to water (50 pounds lecithin in1300 pounds of water). The lecithin/water blend was then sprayed ontothe dry blend of soy protein isolate/Fibersol using techniquesconventional in the agglomeration industry. The water was then removedby heating the resulting blend enough to remove the water but not so asto reduce the solubility of the soy protein. As those of skill in theart will recognize, the length of time needed for this step and thetemperature at which the material is heated, will vary depending uponthe amount of water used, the amount of material to be dried, and thelike. In this instance, the material was dried in three stages over atotal time of about 30 minutes. The first stage was at about 132-138□C.,the second at about 135-141° C., and the third at about 87-94° C. Asstated, the total dry time for the material in this instance was about30 minutes, with approximately 10 minutes at each of the foregoingtemperature ranges.

Ten grams of the dried blend were added to 200 gm. of water in a glass,and stirred. The resulting beverage was free of lumps and was smooth todrink. The Nitrogen Solubility Index was reduced no more than 10%.

The resulting soybean protein granule was evaluated according to Example1 and as a result, it was found that the granule showed approximatelythe same results observed for the granule prepared by spraying asolution of Fibersol 2 and lecithin in Example 1.

The easily dispersible soybean protein granule according to the presentinvention shows the following effects:

1. It can be dispersed in usual liquids for drinking such as water,milk, sour milk beverages and fruit juice drinks, without formingso-called “EDAMA.”

2. It can be dispersed in the foregoing liquids within a short period oftime.

3. Even if one keeps the dispersion in his mouth immediately after thepreparation thereof, it does not have rough feeling to the tongue andeasily passes through the throat.

4. It can eliminate any unpleasant taste such as the smell of soybean,harsh taste, bitter taste and astringency upon drinking the resultingdispersion.

1. A method of dispersing a protein in water, comprising: adding a dryblend comprising a protein and a compound selected from the groupconsisting of an emulsifier, a carbohydrate and a combination thereof towater; and agitating the dry blend in the water, thus dispersing theprotein in the water.
 2. The method of claim 1, wherein the emulsifieris lecithin.
 3. The method of claim 2, wherein the lecithin is selectedfrom the group consisting of crude lecithin, deoiled lecithin and acombination thereof.
 4. The method of claim 1, wherein the carbohydrateis a not readily digestible carbohydrate.
 5. The method of claim 1,wherein the protein is soybean protein or a hydrolyzed soybean protein.6. The method of claim 4, wherein the not readily digestiblecarbohydrate is selected from the group consisting of pine fiber,Fibersol-2, Fibersol-2H, beta glucan, inulin, hemicellulose and anycombination thereof.
 7. A method of preparing easily dispersiblegranules of protein comprising: spray granulating a blend of soybeanprotein, a not readily digestible carbohydrate, and lecithin in water;and drying the blend.
 8. The method of claim 7, wherein the protein issoybean protein or a hydrolyzed soybean protein.
 9. The method of claim7, wherein the not readily digestible carbohydrate is selected from thegroup consisting of pine fiber, Fibersol-2, Fibersol-2H, beta glucan,inulin, hemicellulose and combinations of any thereof.
 10. The method ofclaim 7, further comprising adding salts of calcium or iron to theblend.
 11. The method of claim 7, further comprising adding a compoundselected from the group consisting of sterols, stanols, steryl esters,stanol esters, vitamins, minerals, isoflavones and combinations of anythereof to the blend.
 12. A method of dispersing a protein in water,comprising: mixing a blend comprising a soy protein having a totalprotein content of at least fifty percent by weight, lecithin, and a notreadily digestible carbohydrate with water; and agitating the blend inthe water, thus dispersing the protein in the water.
 13. The method ofclaim 12, where in the protein is soybean protein or a hydrolyzedsoybean protein.
 14. The method of claim 12, wherein the protein contentof protein is at least ninety percent by weight.
 15. The method of claim12, wherein the protein is capable of passing through a sieve of 100mesh at least 90 percent by mass.
 16. The method of claim 12, whereinthe blend is capable of being uniformly dispersed within 5 to 10seconds.
 17. The method of claim 12, wherein the lecithin is selectedfrom the group consisting of deoiled lecithin, crude lecithin, purifiedlecithin and any combination thereof.
 18. The method of claim 12,further comprising mixing a mineral selected from the group consistingof a salt of calcium, a salt of iron, and a combination thereof with thewater.
 19. The method of claim 12, wherein the not readily digestiblecarbohydrate is selected from the group consisting of pine fiber,Fibersol-2, Fibersol-2H, beta glucan, inulin, hemicellulose and anycombination thereof.
 20. The method of claim 12, further comprisingmixing calcium lactate pentahydrate with the water.